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I'll have to read this later since I'm at work but is there a layman's explanation for how these studies distinguish environmental and genetic influence? I don'

I'll have to read this later since I'm at work but is there a layman's explanation for how these studies distinguish environmental and genetic influence? I don't see how you could accurately separate the two.

AstralStorm 8y ago
You don't in this phase, since both feed back into another. After high correlates are found, further experiments will disentangle the relationship.
gwern 8y ago
Not entirely sure what you mean: genes cause environments, and interact with environments. If you mean something like whether it's just picking up ancestry markers for families which happen to be rich etc, there are a lot of methodological components which try to minimize the more obvious ways of population stratification affecting results. The most iron-clad part of showing direct gene->trait causation is the 4 sibling-comparison studies, where you see whether you can predict the difference between 2 siblings; as they have identical ancestries, families, locations etc, their environments are near-identical in the first place, and since meiosis at conception randomizes genes between siblings, success in sibling comparison shows the genes must be causal. IQ GWASes have always passed the within-family test since Rietveld et al 2013, and this is no exception.
- nabla9 8y ago
  > The most iron-clad part of showing direct gene->trait causation is the 4 I would not say it's iron-clad gene->trait causation. Even wth 4 sibling-comparisons and the same environmental factors, it can be gene-environment interaction -> trait Their study finds that genes associated with attainment are active in neurons. These genes might just protect brain from environmental damage. For example: from malnutrition by using nutrients more effectively, infections, heavy metals, or mother smoking or using alcohol, ...
- frgtpsswrdlame 8y ago
  >If you mean something like whether it's just picking up ancestry markers for families which happen to be rich etc, there are a lot of methodological components which try to minimize the more obvious ways of population stratification affecting results. Yeah this is actually what I'm interested in. >The most iron-clad part of showing direct gene->trait causation is the 4 sibling-comparison studies, where you see whether you can predict the difference between 2 siblings; as they have identical ancestries, families, locations etc, their environments are near-identical in the first place, and since meiosis at conception randomizes genes between siblings, success in sibling comparison shows the genes must be causal. IQ GWASes have always passed the within-family test since Rietveld et al 2013, and this is no exception. Couldn't this still lead to an overstating of the effect? So two brothers John and Jim have different builds due to genetics, John is a bit shorter and stockier and Jim is a bit taller and leaner. When they play with each other as children John usually wins when they wrestle and Jim usually wins when they play basketball. They both like winning so in highschool John joins the wrestling team and Jim joins the basketball team. Now if I do some gene testing wizardry on them as adults and try to determine the difference in basketball-skill I'll predict a large gap due to height genes and I'll get one. But part of that skill gap is due to environment (4 years of basketball practice) yet still getting attributed to genes.
  - gwern 8y ago
    > ...When they play with each other as children John usually wins when they wrestle and Jim usually wins when they play basketball... No, this is still genetic causation (and something like this story is usually what is invoked for why the heritability of intelligence increases with age: more intelligent people seeking out niches which then encourage intelligence further rather than preferring to veg out in front of the boobtube, leading shared-environment to disappear while the permanent ongoing influence from genetics leads to heritability increases). What's the definition of causation? It's a 'difference which makes a difference', or in Pearlean terms, if you reach in and do surgery on one node in a causal network, the counterfactual difference. So in your basketball example, what if we reached in with CRISPR, say, and edited just the genes for builds in John to make him taller/leaner? What is the counterfactual of our intervention on the node of genes? As he grows up and becomes taller/leaner, now he still likes winning and playing with his brother is an even challenge, so he joins the basketball team along with Jim and they do well and keep playing and so on and so forth and your basketball PGS predicts less or no difference between them (since we caused them to have the same relevant genes) and indeed there is less or no difference; and if we had instead edited the other way, it'd go the other way etc. Thus, causation. That the causal pathway of the genes goes 'outside the skin', as some people put it, makes no difference that makes a difference for this particular question. (A similar point applies to the 'nature of nurture' findings mentioned in Lee et al 2018 and the two earlier papers. Are they genetic causation? Yes, because if you counterfactually changed the genes and nothing but the genes, you would get different outcomes. They are differences which make a difference. They are, however, causal on things you didn't expect - eg edits in children would cause gains in grandchildren rather than the children.)
rossdavidh 8y ago
Relevant, from the article FAQ: "A recent study of Icelandic families showed that the parental allele that is not passed on to the parent’s offspring is still associated with the child’s educational attainment, suggesting that GWAS results for educational attainment partly represent these intergenerational pathways (Kong et al. 2018). Our sibling analyses yield results that are consistent with this conclusion (see FAQ 2.4)." So, it might just be both environment and the genetic influence both correlating to the same thing, and they admit as much.
polski-g 8y ago
You do a twin study comparing monozgyotic to dizygotic twin pairs. The variance of the trait between the two pairs is the genetic effect. Determining environment effect is done by doing twin-reared-apart studies (to separate shared vs non-shared environment).

AstralStorm 8y ago

You don't in this phase, since both feed back into another. After high correlates are found, further experiments will disentangle the relationship.

gwern 8y ago

Not entirely sure what you mean: genes cause environments, and interact with environments. If you mean something like whether it's just picking up ancestry markers for families which happen to be rich etc, there are a lot of methodological components which try to minimize the more obvious ways of population stratification affecting results. The most iron-clad part of showing direct gene->trait causation is the 4 sibling-comparison studies, where you see whether you can predict the difference between 2 siblings; as they have identical ancestries, families, locations etc, their environments are near-identical in the first place, and since meiosis at conception randomizes genes between siblings, success in sibling comparison shows the genes must be causal. IQ GWASes have always passed the within-family test since Rietveld et al 2013, and this is no exception.

nabla9 8y ago
> The most iron-clad part of showing direct gene->trait causation is the 4 I would not say it's iron-clad gene->trait causation. Even wth 4 sibling-comparisons and the same environmental factors, it can be gene-environment interaction -> trait Their study finds that genes associated with attainment are active in neurons. These genes might just protect brain from environmental damage. For example: from malnutrition by using nutrients more effectively, infections, heavy metals, or mother smoking or using alcohol, ...
frgtpsswrdlame 8y ago
>If you mean something like whether it's just picking up ancestry markers for families which happen to be rich etc, there are a lot of methodological components which try to minimize the more obvious ways of population stratification affecting results. Yeah this is actually what I'm interested in. >The most iron-clad part of showing direct gene->trait causation is the 4 sibling-comparison studies, where you see whether you can predict the difference between 2 siblings; as they have identical ancestries, families, locations etc, their environments are near-identical in the first place, and since meiosis at conception randomizes genes between siblings, success in sibling comparison shows the genes must be causal. IQ GWASes have always passed the within-family test since Rietveld et al 2013, and this is no exception. Couldn't this still lead to an overstating of the effect? So two brothers John and Jim have different builds due to genetics, John is a bit shorter and stockier and Jim is a bit taller and leaner. When they play with each other as children John usually wins when they wrestle and Jim usually wins when they play basketball. They both like winning so in highschool John joins the wrestling team and Jim joins the basketball team. Now if I do some gene testing wizardry on them as adults and try to determine the difference in basketball-skill I'll predict a large gap due to height genes and I'll get one. But part of that skill gap is due to environment (4 years of basketball practice) yet still getting attributed to genes.
- gwern 8y ago
  > ...When they play with each other as children John usually wins when they wrestle and Jim usually wins when they play basketball... No, this is still genetic causation (and something like this story is usually what is invoked for why the heritability of intelligence increases with age: more intelligent people seeking out niches which then encourage intelligence further rather than preferring to veg out in front of the boobtube, leading shared-environment to disappear while the permanent ongoing influence from genetics leads to heritability increases). What's the definition of causation? It's a 'difference which makes a difference', or in Pearlean terms, if you reach in and do surgery on one node in a causal network, the counterfactual difference. So in your basketball example, what if we reached in with CRISPR, say, and edited just the genes for builds in John to make him taller/leaner? What is the counterfactual of our intervention on the node of genes? As he grows up and becomes taller/leaner, now he still likes winning and playing with his brother is an even challenge, so he joins the basketball team along with Jim and they do well and keep playing and so on and so forth and your basketball PGS predicts less or no difference between them (since we caused them to have the same relevant genes) and indeed there is less or no difference; and if we had instead edited the other way, it'd go the other way etc. Thus, causation. That the causal pathway of the genes goes 'outside the skin', as some people put it, makes no difference that makes a difference for this particular question. (A similar point applies to the 'nature of nurture' findings mentioned in Lee et al 2018 and the two earlier papers. Are they genetic causation? Yes, because if you counterfactually changed the genes and nothing but the genes, you would get different outcomes. They are differences which make a difference. They are, however, causal on things you didn't expect - eg edits in children would cause gains in grandchildren rather than the children.)

rossdavidh 8y ago

Relevant, from the article FAQ: "A recent study of Icelandic families showed that the parental allele that is not passed on to the parent’s offspring is still associated with the child’s educational attainment, suggesting that GWAS results for educational attainment partly represent these intergenerational pathways (Kong et al. 2018). Our sibling analyses yield results that are consistent with this conclusion (see FAQ 2.4)." So, it might just be both environment and the genetic influence both correlating to the same thing, and they admit as much.

polski-g 8y ago

You do a twin study comparing monozgyotic to dizygotic twin pairs. The variance of the trait between the two pairs is the genetic effect. Determining environment effect is done by doing twin-reared-apart studies (to separate shared vs non-shared environment).